Color tube with convergence electrode mounting and connecting structure

ABSTRACT

In a single-gun, plural-beam color picture tube in which two beams emerge from a focusing lens along paths that diverge with respect to a central beam emerging along the optical axis of the lens by which all of the beams are focused on the color screen, and the divergent beams are deflected to converge with the central beam by passage through respective electrical fields established between first spaced plates, at opposite sides of the central beam path, and second plates spaced outwardly from the first plates; such plates are disposed closely adjacent to the main deflection yoke by which the beams are made to scan the screen so that the length of the tube can be minimized, and the misconvergence of the beams that would result from a current flow induced in a closed conductive loop that includes the first plates by flux change of the magnetic field of the main deflection yoke is avoided by mounting the first plates in a cantilevered manner at one end and by omitting any conductive connections between the remainder of such plates so that a conductive loop does not exist for the induced current.

United States Patent [72] Inventor Senri Miyaoka 2,921,228 1/1960Famsworth 3 l3/78X Kanagawa-ken, Japan 3,358,172 12/1967 Lewis '313/80[21] Appl. No. 813,938 3,448,316 6/1969 Yoshida et al. 313/70CX [22]1969 Primary Examiner-Robert Segal [45] Patented Apr. 20, 1971 [73]Assign Sony Commfion ArtorneysAlbert Johnston, Robert E. lsner, Lewrs H.

shimgawbku, Tokyo, Japan Eslmger and Alvin Srnderbrand [32] PriorityApr. 13, 1968 [33] Japan 43/24621 ABSTRACT: In a single-gun, plural-beamcolor picture tube [5 in two beams emerge from a focusing along pathsELECTRODE MOUNTING AND CONNECTING that diverge with respect to a centralbeam emerging along the optical axls of the lens by WhlCh all of thebeams are focused STRUCTURE on the color screen, and the divergent beamsare deflected to 5 Claims, 5 Drawing Figs.

converge with the central beam by passage through respective electricalfields established between first spaced plates, at opposite sides of thecentral beam path, and second plates Int. U. paced outwardly from thefirst plates; such plates are 29/82 29/74 disposed closely adjacent tothe main deflection yoke by [50] FleltlOf Search ..3l3/70 (C), hich thebeams are made to scan the screen so that the 73, 80 length of the tubecan be minimized, and the misconvergence of the beams that would resultfrom a current flow induced in [56] References Clted. a closedconductive loop that includes the first plates by flux UNITED STATESPATENTS change of the magnetic field of the main deflection yoke is2,163,233 6/1939 Brown 313/78 avoided by mounting the first plates in acantilevered manner 2,168,892 8/1939 Zworykin 313/80 at one end and byomitting any conductive connections 2,170,944 8/1939 Glass et al....313/78X between the remainder of such plates so that a conductive2,459,724 1/1949 Selgin 313/78X loop does not exist for the inducedcurrent.

l5 1 l I l I /8 e 1 4 P I l F4- 24 L2 23)) 25' PATENTEU AFR20 19mINVENTOR. SENR! MI YAOKA ATTORNEY EG LGR TUBE Wll'llill CONVERGENCEELECTRODE MOUNTING AND CONNECTHNG STRUCTURE This invention relatesgenerally to plural-beam color picture tubes, and particularly to tubesof that type in which the plural beams are passed through the opticalcenter of a common electron lens by which the beams are focused on thecolor phosphor screen so as to eliminate coma and spherical aberrationby reason of the lens.

in plural-beam color picture tubes of the described type, for example,in the single-gun tube as specifically disclosed in the copendingapplication Ser. No. 697,414, filed Jan. 12, 1968 now US. Pat. No.3,448,316 and having a common assignec herewith, three laterally spacedelectron beams are emitted or originated by a beam generating or cathodeassembly and directed in a common substantially horizontal or verticalplane with the central beam coinciding with the optical axis of thesingle electron focusing lens and the two outer beams being converged tocross the central beam at the optical center of the lens and thus emergefrom the latter along paths that are divergent from the optical axis.Arranged between the focusing lens and the color screen is anelectrostatic convergence deflecting means by which the beams divergentfrom the optical axis are deflected substantially in the plane oforigination thereof for causing all of the beams to converge at a commonlocation on a beam selecting means, such as an aperture grill, and topass therethrough for impingement on respective color phosphors of acolor screen. Further, between the focusing lens and the beam selectingmeans, the beams are acted upon by the magnetic fields resulting fromthe application of horizontal and vertical sweep signals to a maindeflection yoke, whereby the beams are made to scanthe screen in thedesired raster. The convergence deflecting means of the foregoing colorpicture tube conveniently comprises a first paid of spaced platesbetween which the central beam is passed, and a second pair of platesspaced outwardly from the first plates so that the divergent beams arepassed between the first and second plates to be deflected forconvergence by electrical fields provided therebetween when one voltageis applied to both first plates and a different voltage is applied toboth second plates.

if the above convergence deflecting plates are to be remote from themagnetic fields of the main deflection yoke, the length of the neck ofthe tube envelope is undesirably increased and requires a correspondingincrease in the depth of the television receiver cabinet to accommodatethe tube. 0n the other hand, if the neck portion of the tube isshortened, which requires that the convergence deflection plates extendclosely adjacent to the main deflection yoke, and if the first platesare interconnected to constitute a closed conductive path, a magneticfield of the main deflection yoke induces a current flow in the closedpath constituted by the interconnected first plates, and such currentflow produces a magnetic field that deflects the central beam away fromaccurate convergence with the other two beams.

Accordingly, it is an object of this invention to provide a plural-beamcolor picture tube of the described type in which the convergencedeflection plates are closely adjacent to, or even axially overlappedwith respect to the main deflection yoke so as to minimize the necessarylength of the neck portion of the tube envelope, and further in whichany misconvergence that would result from the proximity of theconvergence deflection plates to the main deflection yoke is avoided.

ln accordance with an aspect of this invention, the misconvergence thatwould result from the proximity of the convergence deflection plates tothe main deflection yoke is avoided by mounting the first convergencedeflection plates, that is, the plates between which the central beampasses, so that the latter do not constitute parts of a closedconductive loop or path through which an induced current could be madeto flow by a magnetic field of the main deflection yoke.

The above, and other objects, features and advantages of this invention,will be apparent in the following detailed description of illustrativeembodiments thereof which is to be read in connection with theaccompanying drawing, in which:

FIG. 1 is a schematic sectional view in a horizontal plane passingthrough the axis of a single-gun, plural-beam color picture tube of thetype to which this invention is preferably applied;

FIG. 2 is a fragmentary sectional view taken in the same plane as FIG.1, and which shows the structural arrangement of a portion of such tubein order to reduce the length of the neck portion of the tube envelope;

H6. 3 is a transverse sectional view taken along the line 3-3 onFlG. 2;and

H08. 4 and 5 are perspective views showing the arrangements of theconvergence deflection plates in a tube as shown on FIGS. 2 and 3 inorder to avoid misconvergence in accordance with two respectiveembodiments of this invention.

Referring to the drawings in detail, and initially to FlG. 1 thereof, itwill be seen that a single-gun, plural-beam color picture tube 10 of thetype to which this invention may be applied comprises a glass envelope(not shown) having a neck and a cone extending from the neck to a colorscreen S provided with the usual arrays of color phosphors S 5 and S andwith an apertured beam selecting grill or shadow mask G,.. Disposedwithin the neck is a single electron gun A having cathodes K K and Keach of which is constituted by a beam-generating source with therespective beam-generating surfaces thereof disposed as shown in a planewhich is substantially perpendicular to the axis of the electron gun.The beam-generating surfaces are arranged in a straight line so that therespective beams B,,, B and B emitted therefrom are directed in asubstantially horizontal or other common plane containing the axis ofthe gun, with the central beam B),- being coincident with such axis. Afirst grid G, is spaced from the beam-generating surfaces of cathodes KK and K and has apertures g,,,, g,,;, and g, formed therein in alignmentwith the respective cathode beam-generating surfaces. A common grid G isspaced from the first grid G, and has apertures g g and g formed thereinin alignment with the respective apertures of the first grid G,.Successively arranged in the axial direction away from the common grid Gare openended,

' tubular grids or electrodes G,,, G,, and G respectively, with cathodesK,,, K and K grids G, and G and electrodes G,,, G,, and G beingmaintained in the depicted, assembled positions thereof, bysuitable,nonillustrated support means of an insulating material.

For operation of the electron gun of FIG. 1 appropriate voltages areapplied to the grids G, and G and the electrodes G,, G,, and G Thus, forexample, a voltage of 0 to minus 400v. is applied to the grid G,, avoltage of 0 to 500v. is applied to the grid 6,, a voltage of 13 to20kv. is applied to the electrodes G and G and a voltage of 0 to 400v.is applied to the electrode G,, with all of these voltages being basedupon the cathode voltage as a reference. As a result, the voltagedistributions between the respective electrodes and cathodes, and therespective lengths and diameters thereof, may be substantially identicalwith those of a unipotential single beam-type electron gun which isconstituted by a single cathode and first and second, single-aperturedgrids.

With the applied voltage distribution as described hereinabove, anelectron lens field will be established between grid G and the electrodeG to form an auxiliary lens L' as indicated in dashed lines, and anelectron lens field will be established around the axis of electrodeG,,, by the electrodes G,,, G and G to form a main focusing lens L,again as indicated in dashed lines. In a typical use of electron gun A,bias voltages of l00v., 0v., 300v., 20KV. 200v. and 20v. may be appliedrespectively to the cathodes K,,, K and K the first and second grids G,and G and the electrodes G,,, G, and G Further included in the electrongun of FIG. 1 are electron beam convergence deflecting means F whichcomprise a first pair of shielding plates P and P disposed in thedepicted spaced, relationship at opposite sides of the gun axis, and asecond pair of axially extending, deflector plates Q and O which aredisposed, as shown, in outwardly spaced, opposed relationship toshielding plates P and P' respectively. Although depicted assubstantially straight, it is to be understood that the deflector platesQ and Q may, alternatively, be somewhat curved or outwardly bowed, as iswell known in the art.

The shielding plates P and P are equally charged and disposed so thatthe central electron beam B will pass substantially undeflected betweenthe shielding plates P and P, while the deflector plates and Q havenegative charges with respect to the plates P and P so that respectiveelectron beams B and B will be convergently deflected as shown by therespective passages thereof between the plates P and Q and the plates Pand Q. More specifically, a voltage V, which is equal to the voltageapplied to the electrode G may be applied to both shielding plates P andP, and a voltage V which is some 200 to 300v. lower than the voltageV,., may be applied to the respective deflector plates Q and Q to resultin the respective shielding plates P and P being at the same potential,and to result in the application of a deflecting voltage difference orconvergence deflecting voltages between plates P and Q and plates P andQ and it is, of course, this convergence deflecting voltage V which willproduce electric fields to impart the requisite convergent deflection toelectron beams B and B In operation, the electron beams B B and B whichemanate from the beam generating surfaces of the cathodes K K and K willpass through the respective grid apertures g g and g,,,, to be intensitymodulated with what may be termed the red, green and blue intensitymodulation signals applied between the said cathodes and the first gridG,. The respective electron beams will then pass through the commonauxiliary lens L to cross each other at the center of the main lens Land to emerge from the latter with beams B and B diverging from beam BThereafter, the central electron beam 8 will pass substantiallyundeflected between shielding plates P and P since the latter are at thesame potential. Passage of the electron beams 8,, between the plates Pand Q and of the electron beam B between the plates P and Q will,however, result in the convergent deflections thereof as a result of theconvergence deflecting voltage applied therebetween, and the system ofFIG. 1 is intended to be so arranged that electron beams B B and B willdesirably converge or cross each other at a common spot centered in anaperture of the beam selecting grill G, and then diverge therefrom tostrike the respective color phosphors of a corresponding array thereofon screen S. More specifically, it may be noted that the color phosphorscreen S is composed of a large plurality of sets or arrays ofvertically extending red, green and blue phosphor stripes or dots S Sand 8,, with each of the arrays or sets of color phosphors forming acolor picture element. It will be understood that the common spot ofbeam convergence corresponds to one of the thusly formed color pictureelements.

Electron beam scanning of the face of the color phosphor screen iseffected by horizontal and vertical deflection yoke means indicated inbroken lines at D and which receives horizontal and vertical sweepsignals whereby a color picture will be provided on the color screen.Since, with this arrangement, the electron beams are each passed, forfocusing through the center of the main lens L of electron gun A, thebeam spots formed by impingement of the beams on the color phosphorscreen S will be substantially free from the effects of coma and/orastigmatism of the main lens, whereby improved color picture resolutionwill be provided.

As shown on FIGS. 2 and 3, in a structural embodiment of the tubeschematically illustrated on FIG. 1, the plates P and P were supported,at the sides of their ends closest to electrode G,,, by angle members 12and 13 secured to a flange 11 at the adjacent end of a tubular extensionof electrode 0,, which is, in turn, supported within tube neck N byinsulating discs 24 and having getter rings 22 and 23 suitably mountedtherebetween. The forward ends of plates P and P were joined, at thesides of the latter, by conductive bracing members 21 extendingtherebetween. The voltage V,. is applied to plates P and P through acontact spring 18 extending from one of the bracing members 21 intoengagement with a conductive coating 17 which is applied to the innersurface of the cone portion C of the tube envelope and extends into theadjacent neck portion thereof. The voltage V is applied to coating 17 byway of an anode button (not shown) provided in cone portion C, and isapplied to electrode G from plates P and P by way of angle members 12and 13. From electrode G the voltage V may be applied to electrode G; byway of a suitable conductor (not shown). The voltage V may also beapplied to aperture grill G as an anode voltage, by way of coating 17.

Posts or pins 14 extend outwardly from plates P and P and, at theirouter ends, carry glass beads 15 by which plates Q and 2 are supportedwhile being insulated with respect to plates P and P. The voltage V isapplied to plate Q by a conducting lead 20 extending from a button 19 inneck N and the voltage V,, is applied to plate 0' by way of a conductinglead 16 extending between plates 0 and Q and being spaced from plates Pand P.

In order to reduce the necessary length of neck N of the tube envelope,the convergence deflecting means F is located closely adjacent to themain deflection yoke D, and may even axially overlap the location of thelatter as shown on FIG. 2. However, when convergence deflecting means Fis thus located, it is disposed within the magnetic field with verticallines of flux produced by main deflecting yoke D for causing the beamsto horizontally scan the color screen. Since plate P, bracing members21, plate P, angle members 12,13 and electrode G form a closedconductive loop, the magnetic flux changes in such magnetic field ofyoke D induce a current to flow in the closed loop, and the inducedcurrent, in turn, produces a magnetic field between plates P and P thatacts on the central beam B in the direction opposed to the horizontalscanning movement of the beams. Since the other beams B and B are notacted upon by the magnetic field between plates P and P resulting fromthe induced current, at any instant during each horizontal scan thepoint at which beam B reaches the aperture grill G. will lag behind thepoint on the latter at which beams B and B converge, wherebymisconvergence results.

In accordance with this invention, such misconvergence is avoided bymounting the plates P and P so that the latter will not constitute partsof a closed conductive loop in which a current can be induced to flow bya magnetic field of yoke D. Such closed conductive loop is avoided, inaccordance with the invention, by electrically connecting plates P and Ponly at one end thereof.

For example, in the embodiment of this invention shown on FIG. 4, theends of plates P and P closes to electrode G are mounted on flange 11 ofthe latter by flanges 112 and 113 directed outwardly from such ends ofthe plates and having cutouts, as at 1130, through which beams 13,, andB may pass for entering between plates P and Q and plates P and Q. Theopposite or forward ends of plates P and P may be free of each other(FIG. 5) or merely held in spaced relation by members 26 and 27 of anelectrically insulating material. Thus, the forward ends of plates P andP are insulated from each other either by members 26 and 27 or by air.

In order to further brace the plates P and P and to mount the plates Qand Q with respect thereto, metal pins 114a and 11412 are welded,soldered or otherwise secured to opposite longitudinal edges of plate Pto locations spaced apart along the latter, and metal pins 114'a and114b are similarly secured to plate P' at locations that are opposed topins 114a and 114b, respectively. The pins 114a and 11411, and the pins114a and ll4'b extend perpendicular to the planes of the respectiveplates P and P and are of sufficient length, as shown, to extend betweenplates 0 and Q. At the ends of pins 114a and 114'a adjacent plate Q,such pins are anchored in an insulating member traversing the outersurface of plate 0 and being suitably secured thereto, and ends of pins114]; and ll4'b are similarly anchored in an insulating member 15traversing and being secured on the 'outer surface of plate 0. Theopposite ends of pins 114a and l14'a and of pins 11417 and ll4'b aresimilarly anchored in insulating members 15 traversing and being securedon the outer surface of plate 0. Further, plates P and P' have cutoutsor notches 28 and 28, respectively, through which pins 114a and ll4'band pins 114a and 1l4b respectively pass without contacting plates P andP'.

It will be apparent that the above described structure supports plates Qand Q in spaced relation to plates P and P, respectively, while beinginsulated from the latter. Further, such structure, maintains the spacedrelation of plates P and P forwardly of the flanges 12 and 13 formounting an electrode flange 11, while avoiding the formation of aclosed conductive loop that includes plates P and P and in which acurrent could be induced by the proximity of the convergence deflectingdevice F to the yoke D.

In the embodiments of FIGS. 4 and 5, the voltage V,. can be applied toplates P and P by a spring or springs (not shown) similar to the spring18 of FIG. 2, which such plates P and P being electrically connected toeach other only at one end by way of flanges ll, 12 and 13. Further, thevoltage V can be applied to plate 0 in the manner described above inconnection with FIG.- 2, and from plate 0 to plate Q by way of aconductor 116 which is spaced from plates P and P.

Although illustrative embodiments of the invention have been describedin detail herein, it is to be understood that the invention is notlimited to those precise embodiments, and that various changes andmodifications may be made therein by one skilled in the art withoutdeparting from the scope or spirit of the invention.

lclaim:

1. A plural-beam color picture tube comprising a color screen havingarrays of color phosphors, and beam selecting means with aperturescorresponding to said arrays, beam generating means for directing aplurality of electron beams toward said color screen for impingement onrespective phosphors of each array through the corresponding aperture,

between said lens means and said beam selecting means for deflectingsaid two beams emerging along said divergent paths so as to achieveconvergence of all of said beams at an aperture of said beam selectingmeans, and magnetic yoke means also interposed between said lens meansand said beam selecting means for producing a magnetic field by whichsaid beams are simultaneously deflected to scan said screen; saidconvergence deflecting means including first plates which are spacedapart for the passage of said one beam therebetween, second platesspaced outwardly from said first plates so that each of said two beamspasses between a first plate and a second plate and means to apply onevoltage to said first plates and a different voltage to said secondplates so that the voltage difference between said first plates and saidsecond plates produces electrical fields therebetween for effecting saidconvergence, said convergence deflecting means being disposed closelyadjacent to said magnetic yoke means so as to reduce the necessarylength of the tube, said first plates being electrically connected toeach other only at one end to avoid the provision of a closed conductiveloop that includes said first plates andin which a current could beinduced to flow by said magnetic field produced by said yoke means, andinsulating members traversing said second plates and secured thereto atlocations spaced therealong, conductive pins extending between saidinsulating members on one of said second plates and the correspondinglylocated insulating members on the other one of said second plates, eachof said conductive pins being rigidly and electrically connected withonly a respective one of said first plates.

2. A plural-beam color picture tube according to claim 1, in whichinsulating members extend between the other ends of said first plates tomaintain the latter in spaced relation.

3. A plural-beam color picture tube according to claim 1, in

Y which the other ends of said first plates are free of each other andhave an insulating air space therebetween.

4. A plural-beam color picture tube according to claim 1, in which saidconductive pins extend past the opposite longitudinal edges of saidfirst plates, said longitudinal edges have cutouts therein, and each ofsaid pins connected with one of said first plates extends with clearancethrough a respective one of said cutouts in the other of said firstplates.

5. A plural-beam color picture tube according to claim 1, in which saidconductive pins are arranged in pairs extending past the oppositelongitudinal edged of said first plates, with one pin of each of saidpairs thereof being connected with one of said first plates and theother pin of the respective pair of pins being connected with the otherof said first plates.

1. A plural-beam color picture tube comprising a color screen havingarrays of color phosphors, and beam selecting means with aperturescorresponding to said arrays, beam generating means for directing aplurality of electron beams toward said color screen for impingement onrespective phosphors of each array through the corresponding aperture,lens means for focusing said electron beams on said color screen andhaving an optical center through which all of said beams are passed withone of said beams passing through said lens means along the optical axisof the latter and two of said beams being angled with respect to saidoptical axis to emerge from said lens means along paths divergent tosaid axis, electron beam convergence deflecting means interposed betweensaid lens means and said beam selecting means for deflecting said twobeams emerging along said divergent paths so as to achieve convergenceof all of said beams at an aperture of said beam selecting means, andmagnetic yoke means also interposed between said lens means and saidbeam selecting means for producing a magnetic field by which said beamsare simultaneously deflected to scan said screen; said convergencedeflecting means including first plates which are spaced apart for thepassage of said one beam therebetween, second plates spaced outwardlyfrom said first plates so that each of said two beams passes between afirst plate anD a second plate and means to apply one voltage to saidfirst plates and a different voltage to said second plates so that thevoltage difference between said first plates and said second platesproduces electrical fields therebetween for effecting said convergence,said convergence deflecting means being disposed closely adjacent tosaid magnetic yoke means so as to reduce the necessary length of thetube, said first plates being electrically connected to each other onlyat one end to avoid the provision of a closed conductive loop thatincludes said first plates and in which a current could be induced toflow by said magnetic field produced by said yoke means, and insulatingmembers traversing said second plates and secured thereto at locationsspaced therealong, conductive pins extending between said insulatingmembers on one of said second plates and the correspondingly locatedinsulating members on the other one of said second plates, each of saidconductive pins being rigidly and electrically connected with only arespective one of said first plates.
 2. A plural-beam color picture tubeaccording to claim 1, in which insulating members extend between theother ends of said first plates to maintain the latter in spacedrelation.
 3. A plural-beam color picture tube according to claim 1, inwhich the other ends of said first plates are free of each other andhave an insulating air space therebetween.
 4. A plural-beam colorpicture tube according to claim 1, in which said conductive pins extendpast the opposite longitudinal edges of said first plates, saidlongitudinal edges have cutouts therein, and each of said pins connectedwith one of said first plates extends with clearance through arespective one of said cutouts in the other of said first plates.
 5. Aplural-beam color picture tube according to claim 1, in which saidconductive pins are arranged in pairs extending past the oppositelongitudinal edged of said first plates, with one pin of each of saidpairs thereof being connected with one of said first plates and theother pin of the respective pair of pins being connected with the otherof said first plates.